Abstract: We randomly selected 146 flue-cured tobacco samples from 9 provinces in China and 40 abroad to determine the alkaloid contents of flue-cured tobacco leaves by gas chromatography, and its variation pattern，geographical distribution and correlation were analyzed. The results showed that for domestic samples, the alkaloid content variation were wider than that abroad, the contents of total alkaloid and nicotine were high, while the nornicotine, the myosmine, the anabasine and the anatabine alkaloids were low, the alkaloids were ranked from high to low as nicotine, anatabine, nornicotine, anabasine and myosmine. There was a positive correlation among nicotine, nornicotine, myosmine, anabasine and anatabine. There exsisted highly significant difference in alkaloid contents among different leaf positions, which ranked from high to low as B2F, C3F and X2F. In terms of nicotine conversion rates， grades were ranked from high to low as B2F, C3F and X2F. There was highly significant difference in nicotine content and nicotine conversion rates among tobacco leaves from nine provinces. The total alkaloid content were ranked from high to low as Guangxi, Fujian, Hunan, Shandong, Guizhou, Liaoning, Yunnan, Henan and Sichuan, while the Anatabine, nornicotine, anabasine and myosmine; nicotine conversion rates were ranked as Sichuan, Henan, Liaoning, Yunnan, Guizhou, Hunan, Shandong, Fujian, Guangxi. There was a significant correlation between alkaloid content and sensory quality, and nicotine had largest influence on sensory quality, while there were significant negative correlations between nicotine and aroma, after taste, offensive odor, irritancy. But nicotine conversion rates had no significant correlation with sensory quality. There was a significant negative correlation between alkaloid and composite quality. There was no significant correlation between nicotine conversation and composite quality.